Method of coating iron or steel articles



Sept. 3,1935. A. c. SIMMONS 3,364

7 METHOD OF COATING IRON OR STEEL ARTICLES Ill/l ll/ ////////////////l/l//l// lllll/l/ll/l/ll/ A ll Filed July 3, 1933 IKYEHIEIB.

Patented Sept. 1935 I v 2,013,364 I a Ms'rnon oncos'rnvo not: on s'rmn. V 'rrcnnsj Andrew 0. Simmons, Peoria, "Signor, by I mesne assignmenta'to Keystone Steel & Wire Company, Peoria, Ill., 1': corporationof Illinois Application at 3. 933115 No. 878,879 a i I '(ol. iii-70,2)

This invention has reference to the coating of iron or steel articles.

The invention has for its principal object to provide a new and-improved method and appa- 5 ratus for applying a tinned coating to wire and like articles.

The invention has for a further object the tinning of wire and .like' articles without first subjecting the article to a preliminary copper i coat or liquor finish and thereby produce a tinned article where the coating obtained is silver bright, or tin color and also substantially free"- from so-called pin holes or "black spots",

The method, when employed in the tinning of wire, for example, consists in subjecting the wire to a tin bath after first passing the wire through a molten flux of preferably tin chloride known, as tin salt; the subjection of the wire to the tinbath accomplishing both a heating and preliminary tin coating of the wire; then subjecting the pre-heated wire to an additional flux and resubjecting the wire to the tin bath, and removing the wire from such bath through a surface covering of charcoaL- The advantage of coating 3. wire by this method is the fact that the tin coating obtained is silver bright, or tin color in place of having the yellow sheen common to such products which have previously received a copper or liquor finish prior to tinning. Also, by this .method no contamination of the tin bath occurs and hence there is a monetary saving. Furthermore, by the use of a flux on the surface of the tin bath, at its entrance nd, and by the covering of charcoal at its exit end, I am able to reduce the surface exposed to oxidation and hence eliminate sklmmings. By applying the flux to the hot wire there is the added advantage of obtaining a much more thorough fl uxing and cleaning and the result is a product which is freer from pin holes and uncoated area than wire not so treated.

In the practice of the method, I preferably employ a pot containing a bath of molten tin. The surface of the bath at the entrance end, is covered by a covering of molten flux of tin chloride; while the surface of the bath at the exit end is covered by a covering of charcoal. The flux and'the charcoal being retained in their respective locations by a suitable dam. The wire to be tinned is introduced into the bath by first passing it through the flux and into the molten tin. Following its immersion into the molten tin, the wire is carried-around a rotatable. member, as for example a sheave wheel, which is partially submerged in the molten tin and surrounded by the molten'flux oftin chloride; the. finally coated tinned wire being removed from the bath through the covering of charcoal at the exit end of the bath.

In the accompanying drawing I have illustrat- 8 ed more or less diagrammatically one typical pot construction which can be utilized for the practice of the invention, said drawing representing a vertical longitudinal section through the pot. Referring to this drawing, the pot which is des- '10 ignated I in its general construction anddesign is not unlike pots intended for similar uses and may be gas-fired or otherwise heated for keep- 7 ing the coated metal ,in a molten state; Ex-

tending transversely across the pot, at a suitable point mediate its ends and depending therein for a predetermined distance from its upper edge, is a dam 2. Partially submerged within the pot and partially projecting thererwi-thout, in the entrance end of the pot, are supported a plurality of preferably individual sheave wheels 3. In the present disclosure only one sheave wheel appears, but it is understood that such wheels are disposed in a series on a shaft 4 supported by the pot, the wheels being as close or in such spaced relation as practice may dictate and of any number desired. I prefer that the wheels be adapted to rotate on the shaft and the shaft held stationary. Also within the pot at the entrance -as well as at the exit ends are guides 5 and 6,

respectively; The pot so constructed is filled with molten tin 'I, the level of which is normally below the upper edge of the pot and extends up on either side of the dam 2, and has partially submerged therein the sheave wheels 3. The surface of the molten tin, on the entrance end of the pot is covered'with a molten flux of tin chloride 8 whichsurrounds the sheave wheels at their point of entrance into and emergence from the molten tin. The surface of the molten 40 tin, on the exit end of the pot is covered with a charcoal 9.

The drawing shows the direction and path of travel of awire A into and through the tin bath and once around the sheave wheels 3; the wire passing first, through the molten flux of tin chloride 8, thence into the molten tin'l, thence around the sheave wheel 3, reentering the molten tin through the flux, in a molten state, and thence again through the molten tin and out through the charcoal 9, the wire being guided into the molten tin by the guide 5 and out of the molten tin by the guide 6. I utilize a plurality of sheave wheels 3, one for each wire, in preference to a single drum. This is an advantage,

due to the fact that a plurality of wires passing through the bath simultaneously travel at differrotate on their support, These wheels furthermore, impart a snubbing action to the wire within the bath which tends to straighten the wire and steady its passage through the wiping mechanism (not shown)-.

The method herein disclosed of tinning wire, which employs the principle of applying a hot flux to the pre-heated wire has the advantage of extra cleaning or fluxing on the surface of the wire and the action of the flux on the top of the bath is a great deal more active than the cold flux which precedes the metal finishing. Such a flux of tin chloride, has the ability to reduce the iron oxidized surface of the wire. In other words, it acts as a pickle right on the surface of the bath. A flux applied in this manner not only cleans the wire from any oxidized surface, but keeps the wire in this condition until it may be acted upon by the action of the molten tin.

Wire which has been pickled and allowed to dry in the air oxidizes slightly. Because of the fact that the flux is right on the surface of the molten tin, the wire does not have any period of exposure to the air when fluxed with the molten The flux upon the surface of the bath and the charcoal at the exit end have the following advantages: Both reduce or eliminate the formation of tin oxide and the charcoal retains the heat in the bath. Charcoal is employed in preference to any other material, which would haveinsulating qualities, because it does not con taminate the surface, nor is it drawn out upon the wire as it emerges from'the bath; Also, the

. copper or liquid coat preliminary to the tin coat-- ing requires the user to bail out the tin pots peri-' odically, whenever the tin content reaches a certain percent. Tin so removed is sold at a scrap penalty, and consequently results in a loss. This objection is also obviated by the use of my method. Itis claimed by some thata 0.5% copper contamination issufiicient to cause 'the Wire to have a brittle tin coating which, of course; is not to be desired. By the use of my method this condition will not prevail because the tin bath does not become contaminated and therefore, the coating which I am enabled to produce is very ductile and there is never any doubt as to the point or percentage when it is necessary to replace the tin in the pot.

The method disclosed will produce somewhat the same effect as would beproduced if the wire was tinned once and then running the wire through a bath a second time, except that the latter practice is slow, inconvenient and thereby costly. The advantage I have with my method is,

that, I apply the flux to a pre-heated wire and thereby I obtain a more thorou'gh fluxing and cleaning and this results in a product which is freer from pin holes and uncoated area than wirenot so treated and coated.-

The article produced by this method and in particular if article is wire, is intended for various and different uses. For example, if the coated wire is used in the construction of articles of manufacture like fly swatter s, the bright tin coat has the advantage in making the article more salable. On the other hand, if the tinned wire is used for culinary articles, then the tin not only has the advantages previously referred to,

but acts as a protective coating morev or less hygienic in such uses.

What I claim is:-

The method of coating iron or steel wire, with tin and without preliminarily coating the wire with a copper or liquor or other finish, which resides in initially heating the wire and then while so heated passing the wire through molten flux that is superimposed upon a bath of molten tin whereby to cause the flux to directly contact with the wire, then in passing the wire through the molten tin bath, out of the latter through the flux and then again intothe same molten tin bath and finally passing the wire through a layer of charcoal superimposed upon said molten tin bath.

ANDREW C. SIIVINIONS. I 

